scale-serialization 1.0.0

SCALE Serialization
Documentation 
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#![cfg_attr(not(feature = "std"), no_std)]
//!
//! # Scales
//!
//! Dynamic SCALE Serialization using `scale-info` type information.

#[cfg_attr(feature = "serializer", macro_use)]
extern crate alloc;

#[cfg(feature = "scale-info")]
pub mod compress;
pub mod error;
pub mod registry;
#[cfg(feature = "serializer")]
mod serializer;
#[cfg(feature = "text")]
mod textfmt;
mod value;

pub use error::Error;
pub use registry::{Registry, TypeDef, TypeId};
#[cfg(feature = "json")]
pub use serde_json::Value as JsonValue;
#[cfg(feature = "serializer")]
pub use serializer::{to_bytes, to_bytes_with_info, to_vec, to_vec_with_info, Serializer};
#[cfg(all(feature = "serializer", feature = "json"))]
pub use serializer::{to_bytes_from_iter, to_vec_from_iter};
#[cfg(feature = "text")]
pub use textfmt::{from_text, to_text};
pub use value::{Cursor, FieldIter, SeqIter, TupleIter, Value};

mod prelude {
    pub use alloc::string::{String, ToString};
    #[cfg(feature = "serializer")]
    pub use alloc::vec::Vec;
}

// adapted from https://github.com/paritytech/parity-scale-codec/blob/master/src/compact.rs#L336
#[cfg(any(feature = "serializer", feature = "text"))]
#[allow(clippy::all)]
pub(crate) fn compact_encode(n: u128, mut dest: impl bytes::BufMut) {
    match n {
        0..=0b0011_1111 => dest.put_u8((n as u8) << 2),
        0..=0b0011_1111_1111_1111 => dest.put_u16_le(((n as u16) << 2) | 0b01),
        0..=0b0011_1111_1111_1111_1111_1111_1111_1111 => dest.put_u32_le(((n as u32) << 2) | 0b10),
        _ => {
            let bytes_needed = 16 - n.leading_zeros() / 8;
            debug_assert!(bytes_needed >= 4);
            dest.put_u8(0b11 + ((bytes_needed - 4) << 2) as u8);
            let mut v = n;
            for _ in 0..bytes_needed {
                dest.put_u8(v as u8);
                v >>= 8;
            }
        }
    }
}

/// Decode a hex string (without `0x` prefix) into bytes.
#[cfg(any(feature = "serializer", feature = "text"))]
pub(crate) fn decode_hex(hex: &str) -> Result<alloc::vec::Vec<u8>, Error> {
    if !hex.len().is_multiple_of(2) {
        return Err(Error::BadInput("odd number of hex digits".into()));
    }
    hex.as_bytes()
        .chunks(2)
        .map(|pair| {
            let hi = hex_nibble(pair[0]).ok_or(Error::BadInput("invalid hex digit".into()))?;
            let lo = hex_nibble(pair[1]).ok_or(Error::BadInput("invalid hex digit".into()))?;
            Ok((hi << 4) | lo)
        })
        .collect()
}

#[cfg(any(feature = "serializer", feature = "text"))]
#[inline]
fn hex_nibble(b: u8) -> Option<u8> {
    match b {
        b'0'..=b'9' => Some(b - b'0'),
        b'a'..=b'f' => Some(b - b'a' + 10),
        b'A'..=b'F' => Some(b - b'A' + 10),
        _ => None,
    }
}

#[cfg(test)]
mod tests;